Elyse and Victoria collected postcards. Elyse gave 25% of her postcards to Victoria and as a result, Victoria's postcards increased by 30%. If Elyse had 72 postcards left, find the number of postcards Victoria should give to Elyse in the end so that both had an equal number of postcards.

	Elyse	Victoria	Comparing the change in Victoria's postcards
Before	4x3 = 12 u		10x1 = 10u
Change	- 1x3 = - 3 u	+ 1x3 = + 3 u	+ 3x1 = + 3 u
After	3x3 = 9 u		13x1 = 13 u

25% = ²⁵₁₀₀ = ¹₄
30% = ³⁰₁₀₀ = ³₁₀

The increase in the number of postcards that Victoria had is repeated.  Make the increase in the number of postcards that Victoria had the same. LCM of 1 and 3 = 3

9 u = 72

1 u = 72 ÷ 9 = 8

Number of postcards that Victoria had more than Elyse in the end
= 13 u - 9 u
= 4 u

Number of postcards that Victoria should give to Elyse so that both had an equal number of postcards in the end
= 4 u ÷ 2
= 2 u
= 2 x 8
= 16

Answer(s): 16